Rheostat



ous types of discs employed.

Patented Aug. 7, 1928.

UNITED STA-TENS;

won r. NEAL, or mnmnnronrs, mnnuve.

BHEOSTAT.

- I Application filed otober18, 1926. Serial No. 142,512.

invention" pertains to an improvement in rheostats, and particularly to that -t e of rheostats controlled by ressure.

en to con-' eretofore the practicehas struct rheostats of this type varying under ressure in the area of contact principally as tween a plurality of discs mounted in a suitable tubular casing one upon the other and' the coil spring-type of rheostat. vIn such cases the construction and operation of the rheostat has been such that the discs are always in contact with each other, but the area of such contact is varied by increasing or diminishing the pressure exerted thereon. The object of this invention is to provide a rheostat which may be conveniently and commercially made by mounting a plurality of perforated discs on a centrally extending insulating rod, said discs being so arranged and formed with respect to each other as to vary the resistance by varying the number of contacts under pressure rather than the surface area, as well as changing by variation in pressure from a series of contacts to a series of parallel contacts. This permits of a small and convenient'rheostat having a wide range of resistance variation.

The full nature of the invention will be understood from the accompanying draw-' ings and the following description and claims.

Fig. 1 is a central vertical section through the rheostat. Fig. 2 is a diagrammatical illustration of the arrangement of the vari- Fig. 3 isan enlarged side elevation of one of the plain discs showing an exaggerated distortion.

Fi 4 is a side elevation of one ofthe ra ially split discs showing its radial'wings in exaggerated position. Fig. 5 shows a modified form of the invention. 1

In the drawings there is shown a rheostat comprising a tubular casing having its ends closed by the insulating blocks 11 and 12. Rigidly secured intermediate the ends between the blocks 11 and 12 there is a central supporting rod 13 which may be of any,

suitable insulating material, preferably a glass tube. Secured to the end block 11 there is a contact disc 14 provided with a terminal 15 extending through the disc 11 to which may be secured a lead wire 16. Adjacent the end block 12 there is a contact block 17 to which' is secured the terminal 18 for receiving the wire 19. The block 12 and disc '17 are screw threaded to receive the threaded pressure screw 20 having a handle or dial 21 thereon, said screw being hollowed out so as to pass over the rod 13 and engage the movable contact block 22.

Intermediate the block 22 and the contact disc 14: there are a plurality of resistance varying discs slidably mounted and supported upon the rod '13. Said discs comprise a series of units, each unit consisting of a set of discs as illustrated in Fig. 2. As shown therein, a disc of a comparativel large diameter and slightly deformed as i lustrated in Fig. 3 is positioned adjacent a similarly deformed disc B of lesser diameter following which there is positioned a disc C of still lesser diameter which is interposed between the disc C and disc D having the same diameter as the disc B but provided with a plurality of radial slots forming opposite and outwardly bent wings 23. A disc C is positioned on the opposite side of thedisc D and following the same there is another disc B after which is positioned the disc-E which is formed in a similar mansame as the disc A. A similar grouping of the same types of discs follows as illustrated. It will be noted that the discs A and E are the same diameter, one having the split wings while the other is slightly deformed. The discs B and D are the same diameter and differ in the same respects as above her to disc D but of a larger diameter or the Upon the pressure being slightly increased,

the discs C are short circuited by direct contact being made between discs B and D. At the same time, the current may also pass through the discs C as Well so as to provide a series of parallel contacts, i. e., discs B and D and discs B, C and D. When the greatest pressure is applied the current may pass directly between the discs A and E short circuiting the discs B, C and D, thus greatly decreasing the resistance. At the same time the current may also pass through'all of the discs A, B, C, D and E so as to provide a series of parallel contacts, whereby as the I pressure increases the resistance changes from-a slngle ser1es of contacts .to a series of parallel contacts. By contmned increase of pressure or pressures intermediate the threepressures above mentioned, there will be a variation of the contacting areas between" the discs of the character employed in the prior art. From the above it will be observed that in a single unit as illustrated in Fig. 2, with a slight pressure there will be a single series of 12 contacts through which the current must pass. By the intermediate pressure being exerted, not only will there be a variation in the area of contact, but the number of contacts will be reduced to 8 contacts in addition to the 12 contacts, so as to provide a series of parallel contacts. Upon the greatest pressure being exerted, the number of contacts in the unit shown in Fig. 2 will be decreased to two contacts. At the same time, in addition to the variation in the number of contacts, as Well as the series of parallel contacts, there will be a variation in provided a tubular casing-110 in which are mounted a plurality of discs A, B, C, D,

1 and E, the discs A and E having their central portions extending inwardly so as to surround the abuttin abut each other, while the discs B, C and D are perforated in their .centers so as to projections of the discs B, C and D discs A and E. Sai

are distorted so as to exert a spring-like ef fect, between discs A and E for normally maintaining their adjacent centers in spaced Upon a greater pressure being applied the current will be caused to pass through the discs A, B and D shorting out the discs C.

Upon a still greater pressure being applied, the current will pass directly from the discs A to the discs E, wherefore substantially the same action would be obtained as above ported adjacent each other whereby an electric current may be passed between each of 1 said contacting discs, and means for applying pressure thereto for causing some of said members to be short circuited by others for yarying the number of electrical contacts 1n said rheostat.

2. A rheostat comprising a plurality of contact discs varying in diameter, positioned therein, some of said discs having distorted surfaces, and means for forcing said discs together under pressure for causing the discs of larger diameter to contact directly with each other and short circuit the intermediate discs of. smaller diameter for varying the number of electrical contacts in said rheostat.

3. A rheostat comprising a plurality of annular discs varying in diameter formed of metal stampings and having central apertures therethrough, a rod upon which said discs are slidably mounted, and means for exerting a pressure on said discs for varying their area of contact and causing some of said discs to be directly contacted with each other for short circuiting other of said discs and thereby varying the number of electrical contacts of said rheostat.

. .4. A rheostat comprising a plurality ofcontacting members varying in diameter,

each of said members being provided with a central aperture, an insulating rod mounted in said rheostat and extending through said apertures for slidably supporting said members thereon, and means for varying the pressure exerted'between said members for causing some of said members to short circuit others and vary the number of electrical contacts in said rheostat.

6. A rheostat comprising a plurality of plain discs, a plurality of intermediately positioned discs rovided with'laterally extending portions a out the periphery thereof, intermediate discs of smaller diameter, and means for exerting a pressure between said discs whereby said first mentioned discs will make electrical contact with each othcrindependently of said intermediate disc of lesser diameter for short circuiting the same and decreasing the number of electrical contacts in said rheostat.

7. A rheostat comprising a plurality -of plain discs, a plurality of intermediately positioned discs provided with laterally extending portions about the periphery thereof, intermediate discs of smaller diameter, each of s aid discs being provided with a central aperture, an insulating rod mounted in said rheostat for supporting said discs thereon, and means for exert-ing a pressure between said discs whereby said first mentioned discs will make electrical contact with each other independently of said intermediate disc of lesser diameter for short circuiting the same and decreasing the number of electrical contacts in said rheostat.

8. A rheostat comprising a lurality of i slidably mounted contact mem rs, means for supporting said members normally in contact with each other, and means for applying pressure to said members for causmg some of said members to short-circulted by the direct contact of the members lyingmon either side thereof for varying the num r of electrical contacts in said rheostat.

- In witness whereof, I have hereunto affixed m si ature.

y gn LEON P. NEAL. 

